Garda and military intelligence units have increased their monitoring of suspected jihadi sympathisers based here in an attempt to prevent the spread of violent attacks to this country.

Senior security advisers are particularly concerned at the rise in the number of ‘lone wolf’ strikes on mainland Europe.

For some time, officers have been convinced that the most likely threat of an international terrorist incident would emerge from a loner who had been radicalised over the internet.

As a result, specialist sections of the Garda and the Army have been keeping a close watch on the activities of the listed suspects to determine if they have been involved in either attempting to attract fresh support from vulnerable young people now living here or encouraging others to become involved in violence.

The growing frequency of the attacks in countries such as France and Germany is also being kept under review by Taoiseach Enda Kenny, Tánaiste Frances Fitzgerald and other relevant government ministers.

A spokesperson for Ms Fitzgerald said Ireland “cannot consider itself immune from the threat posed by international terrorism and extremism.

“Combating terrorism is a top priority for the Tánaiste and the additional €55m provided to An Garda Síochána a few weeks ago took into account the extra demands arising from measures to deal with the threat from international terrorism,” the spokesperson said.

The threat level in Ireland had been raised from low to moderate early last year in the wake of the Charlie Hebdo murders in Paris.

It has not been changed since then, despite the Bataclan and other attacks on that city in November and subsequent atrocities.

Ireland has vowed to play its part in the EU response to jihadi terrorism and the onus is on the Garda anti-terrorist units and military intelligence to keep a tight watch on the movements and contacts of the small group of Isil supporters based in this country.

Ireland has been used in the past as a base for logistics support, with sympathisers raising funds, providing crucial documentation – such as forged passports and identity cards – and helping al-Qa’ida activists who wanted to lie low for a while.

Gardaí are also in regular liaison with their counterparts in both in the UK and continental Europe in relation to tracking the movements of suspects and sharing intelligence.